Activation of hydrogen peroxide bleach solutions with peroxydiphosphate

ABSTRACT

Bleaching of textile fabrics with aqueous alkaline hydrogen peroxide is improved by the addition to the bleach liquor of small amounts of peroxydiphosphate.

United States Patent [151 3,649,164

Yelin et al. 1 Mar. 14, 1972 [54] ACTIVATION OF HYDROGEN [56] References Cited PEROXIDE BLEACH SOLUTIONS WITH PEROXYDIPHOSPHATE UNITED STATES PATENTS [72] Inventors: Robert E. Yelin; Leonard A. Sitver, both 2 :2 21 of Willingboro; Ralph F. Villiers, Trenton, g an of Primary Examiner-Mayer Weinblatt Assigneel FMC Corporation, New York, Attorney-Milton Zucker, Frank lanno, Eugene G. Seems and 22 Filed: Aug. 21, 1970 Pauhne Newman 211 App]. No.2 66,056 57 ABSTRACT Bleaching of textile fabrics with aqueous alkaline hydrogen [52] US. Cl ..8/l1l, 252/95, 252/186 id i im roved by the addition to the bleach liquor of [5 l 1 Int. Cl. small amounts of peroxydiphosphate, [58] Field oiSearch ..8/l1l; 252/95, I86

3 Claims, N0 Drawings ACTIVATION OF HYDROGEN PEROXIDE BLEACH SOLUTIONS WITH PEROXYDIPI-IOSPHATE BACKGROUND OF THE INVENTION 1. Field of the Invention:

This invention is directed at improving the bleaching of textiles with aqueous alkaline hydrogen peroxide.

2. Review of the Prior Art:

Bleaching of fabrics and fibers with hydrogen peroxide is well-established practice. Conventionally, the scoured and desized textile is caused to absorb an aqueous alkaline bleaching solution containing hydrogen peroxide, caustic soda, often with sodium silicate and a wetting agent, and with chelating agents to prevent metal precipitation. The saturated fabric is then treated at elevated temperatures approaching the boiling point, which may be elevated well above 212 F. by the use of pressure. Effective bleaching is obtained, with excellent results.

Cool bleaching, at temperatures below 120 F gives fabrics with lower absorbency than hot-bleached fabrics. This difficulty is overcome, in accordance with Gallagher et al. US. Pat. No. 3,026,166 issued Mar. 20, 1962, by adding to the bleaching solution a small amount of a soluble peroxydisulfate, which not only overcomes the loss of absorbency due to cold bleaching, but increases brightness by about 2 reflectance points. However, attempts to use peroxydisulfate in hot-bleaching to increase brightness have not met with commercial acceptance. Although improved brightness is obtained, the process is tricky. The peroxydisulfate decomposes rapidly in the bath in the 90 to 160 F. range which is generally used in saturating the textile; the decomposition produces acid which changes the pH of the bath, and there is some evidence of undesirable cellulose degradation.

STATEMENT OF THE INVENTION We have discovered that consistent improvements in brightness, of the order of 2 reflectance points, can be obtained in high-temperature bleaching of cellulosic and other fibers with alkaline hydrogen peroxide, by adding to the bleaching bath about 0.05 to 0.5 percent of a soluble peroxydiphosphate. The consistent increase in brightness is accompanied by a marked decrease in fats, oils, waxes and sizing, resulting in more rapid and more uniform fabric absorbency.

DETAILED DESCRIPTION OF THE INVENTION This invention is applicable to the bleaching of cellulosecontaining textiles such as cotton, linen, rayon and the like, and blends of these fibers with synthetics. Generally, the textiles are spun into yarns, after which sizing agents such as starch or other polymers which aid in processing are applied; the yarns may be bleached or made into fabrics. The so-called greige goods are then desized and scoured, and bleached. Maximum brightness in the bleached fabric without injury to the fabric by cellulose degradation is wanted, and rapid and uniform absorbency is also desired, for subsequent finishing and dyeing operations.

In bleaching with hot alkaline hydrogen peroxide, the desized and scoured fabric is caused to absorb an aqueous alkaline hydrogen peroxide solution, which generally contains about 0.5 to 1.5 percent of hydrogen peroxide, based on weight of material (percent OWM), and sufficient alkali to get the pH up to the range of about 9 to 14, generally by a combination of caustic soda and sodium silicate. Wetting agents are conventionally used to insure fast wet-out of the textile; they may be anionic, cationic or nonionic. Most mills use chelating agents to prevent interference by trace metals during processing. The textiles are preferably padded with a hot solution, at temperatures of 140 to 160 F. The saturated fabric is then heated to the boiling point. In a J-box, this is of course 212 F; bleaching time is about 1 minute to 2 hours. Higher temperatures can be obtained in high-pressure apparatus, such as the Vapor-lock in a typical 45 psi. treatment at 275 F, time required is about 10 seconds to minutes.

After bleaching, the chemicals are rinsed out of the textile, and the product further treated as required.

In accordance with this invention, we add about 0.05 to 0.5 percent OWM of a water-soluble peroxydiphosphate to the bleach, to get an increase in brightness which cannot be obtained by adding the same amount of active oxygen as hydrogen peroxide, together with a decrease in the noncellulosics (fats, oils, waxes and sizing) present in the textile material. In general, an increase of about 2 points in reflectance is obtainable with about 0.2 to 0.3 percent of peroxydiphosphate; at the same time, the noncellulosics are reduced to about 60 to percent of the values obtained without the peroxydiphosphate.

No other changes in processing are necessary; all that is required is the addition of the necessary amount of peroxydiphosphate to the bleaching solution.

SPECIFIC EXAMPLES OF THE INVENTION The following examples of the invention are given by way of illustration, and not by way of limitation.

Example 1 Prior Art for Comparison A sample of percent cotton Oxford was bleached with 2.1 percent (50 percent) hydrogen peroxide, 0.15 percent sodium hydroxide, 1.0 percent silicate (sodium) and 0.1 percent Triton X-lOO (wetting agent) at 212 F. for 60 minutes. The reflectance obtained was 86.3 percent. Percentages are on weight of fabric. Fabric was saturated to 100 percent wet pickup at room temperature and steamed.

This Invention A similar sample of cotton Oxford was bleached with the same formulation, and under the same conditions as above, but 0.2 percent tetrapotassium peroxydiphosphate was added to the bleach solution. An increase in reflectance of 2.3 points, to 88.6 percent was obtained.

Example 2 Prior Art for Comparison A sample of 100 percent cotton Oxford was bleached as in Example 1, but with 1.05 percent (50 percent) hydrogen peroxide, and the reflectance obtained was 85.9 percent.

This Invention The addition of 0.2 percent tetrapotassium peroxydiphosphate to this bleach formulation gave an increase of 1.7 reflectance points to 87.6 percent.

Example 3 Prior Art for Comparison A sample of 65/35 polyester/cotton fabric was bleached with 2.1 percent (50 percent) hydrogen peroxide, 1.75 percent silicate (sodium), 0.30 percent sodium hydroxide and 0.1 percent Triton X-100 (wetting agent) at 212 F. for 60 minutes. The total reflectance obtained was 95.2 percent.

This Invention A similar sample of polyester/cotton fabric was bleached as above, but 0.2 percent tetrapotassium peroxydiphosphate was added to the bleach solution. The reflectance increased from 95.2 to 97.3 percent.

Example 4 Prior Art for Comparison In a mill trial, a 100 percent cotton terry toweling was bleached with 1.3 percent sodium hydroxide, 1.34 percent sodium silicate, 2.3 percent (35 percent) hydrogen peroxide, 0.03 percent wetting agent, and 0.039 percent chelating agent. A reflectance of 86.4 percent was obtained.

This Invention An identical trial was held as above, but 0.3 percent tetrapotassium peroxydiphosphate was added to the bleach formulation. An increase in reflectance of 2.0 points was measured.

The fabric (terry toweling) after the bleach in Example 4, without peroxydiphosphate added, was found to have a combined enzyme-andawater extractable of 0.063 percent as determined by AATCC test method 97-1960T. The terry ills a period of time for the peroxide to react, the improvement which comprises having present in the aqueous solution from 0.05 to 0.5 percent on weight of textile material, of a water- :soluble peroxydiphosphate.

2. The method of claim I, in which the peroxydiphosphate content is between 0.2 and 0.3 percent.

3. The method of claim 1, in which the reaction is carried out near the boiling point.

U i i k t 

2. The method of claim 1, in which the peroxydiphosphate content is between 0.2 and 0.3 percent.
 3. The method of claim 1, in which the reaction is carried out near the boiling point. 